The present invention generally relates to a visual indicating device for use in articles that control and absorb odors, and in particular, odors such as foot odor, urine odor, feces odor, garbage odor, tobacco odor and raw meat odor. The invention also relates to an odor absorbent article including such an indicating device.
Several products have been developed for odor control, most of which are based on odor masking, odor absorption or the degradation of odor forming compounds. In products where the odor is controlled through odor absorption, the user generally has no idea as to whether the odor absorbing article is working or not, other than by the slow removal of the offending odor. Thus, when the odor absorbing product has become saturated and needs to be replaced, the user would only become aware of this when the product stops absorbing the odor and the offending odor becomes noticeable. It would therefore be advantageous for the user to be made aware of the fact that the article was saturated and needed replacing prior to this situation arising.
In some situations it would also be advantageous if the user could be made aware that a odor is present, even though it was being absorbed and was not noticeable, so that the user could take steps to remove the cause of the odor, or could feel more at ease that the product was working efficiently.
U.S. Pat. No. 5,733,272 to Brunner et al. teaches the use of a fragrance or perfume to indicate that an odor is being removed. This fragrance is moisture-activated, and the scent is released in small bursts when wetted. U.S. Pat. No. 6,369,290 to Glaug et al. and PCT International Publication No. WO 98/26808 to Trinh also disclose the release of a fragrance to indicate that an odor is being removed.
However, the use of a fragrance is not always desirable, as not all users will find a fragrance to be pleasant, and there may be situations where the user would prefer the indicator to be a discreet type of indicator, rather than the release of a fragrance which could be detected by others. Such a system also does not indicate to the user when the odor absorbing product is saturated and needs to be replaced.
EP Patent No. 1 157 672 to Carlucci et al. discloses a liquid and odor absorbent structure for inanimate places such as refrigerators. The patent mentions that the structure may be provided with an indicator to indicate the end of the life time of the structure, but goes no further than this in regard to the indicator, except to mention that the indicator would be a conventional indicating means known to those skilled in the art.
PCT International Publication No. WO 00/76558 to Persson describes the use of a visual indicator to indicate the activity of an active ingredient in an absorbing article. The visual indicator changes color in response to a change in the active additive in the absorbing article. This change in the activity of the active additive could be as a result of a number of reasons, for example a change in the environmental conditions.
The inventors are not aware of any existing visual indicating system which is suitable for use on an odor absorbent product and which changes color in direct response to an odor.